Effects of Permanent Crops and Fallowing on the Thermal and Optical Properties of Typical Chernozem.

The humus-accumulative horizon of a typical chernozem (Haplic Chernozem (Loamic, Pachic)) under different land uses has been studied with the thermal method and IR spectroscopy. According to our data, the organic matter of chernozem mainly consists of thermally weakly stable aliphatic compounds, such as polysaccharides. This is indicated by a considerable weight loss (68.15–71.54%) in the low-temperature region, which varies and an intense absorption band at 1083 cm–1, which determines the shape of the IR spectra of chernozem. An extensive agricultural use has caused the mineralization of labile aliphatic compounds and an increase in stable cyclic structures in the composition of the organic matter of chernozem. This is indicated by a decrease in the Chernikov–Konchits Z coefficient from 3.16 to 2.47–2.73 and in the intensity of most absorption bands in the IR spectra. The most pronounced negative impact on the organic matter of a typical chernozem is caused by bare fallow. [ABSTRACT FROM AUTHOR]